This invention relates to a power transmission means, e.g., to achieve drive between an input and an output shaft, allowing for continuous variation of the drive between these shafts, even while the means of the invention is rotating. The transmission means of the invention relates in a preferred form to positive drive variable ratio power transmission means utilising gear teeth or the like in overall constant mesh between input and output members, the ratios nonetheless being continuously variable while the transmission means is rotating.
Variable ratio power transmission means are known which produce a substantially continuous variation of ratios between an input and an output, for example by the VARIOMATIC (trade mark) belt drive transmission adopted in DAF (trade mark) motor cars and the Perbury type gear which utilises disc rollers bearing against toroidal members. Both means rely on friction for their drive and their continuous variability of drive ratio. Positive drive gearboxes have hitherto provided variable ratios but not without a discontinuity or disrruption of transmission between input and output.